Transfer printing technique aims to transfer patterns and texts on a carrier film to a targeted object by pressure to generate appearance diversity of the object. Advance of technology makes transfer printing technique widely adopted on the surface of many types of material, such as metal, glass, plastics, ceramics and the like.
Among the transfer printing techniques, thermal transfer printing technique is most widely adopted. It adopts a principle by printing a pattern to be transferred on a heat-resistant base film, disposing the base film contained the pattern on the surface or location of a targeted object, and applying heat and pressure to transfer the pattern to the targeted object. In the conventional thermal transfer printing, the printing layer of the pattern is directly exposed outside after the transfer printing process is finished. As the printing layer is generally made from a soft material and easily chaps and peels off upon abrasion or impact with other articles. Hence the thermal transfer printing quality and life span are easily affected. To provide protection, the conventional approach is forming a protection film by spraying after the thermal transfer printing has been finished. However, spraying process not only creates environmental pollution also consumes a great amount of spraying material and results in a higher production cost.
To remedy the aforesaid drawbacks, an In-Mold Decoration (IMD) technique has been developed to form a desired pattern on the object surface. Its process includes disposing a film formed with a hardened layer and a decorative pattern in an injection mold, and injecting a thermal resin to one side of the film in an injection process so that the thermal resin and the film are bonded together in one body. While such a technique allows the decorative pattern to be covered by the hardened layer without directly exposed and damaged or scraped, applied to a cubical mold with a great curved angle chaps are prone to occur, and creases or air bubbles could be generated. Hence its applicability is limited.